Research has verified that yawning is caused by too little oxygen and too much carbon dioxide in the bloodstream.

Name: Research has verified that yawning is caused by too little oxygen and too much carbon dioxide in the bloodstream.
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Question

Quizplus · Accepted Answer

While there are different theories about why people yawn, research has not definitively proven that it is caused by too little oxygen and too much carbon dioxide in the bloodstream.

Research Has Verified That Yawning Is Caused by Too Little